//===- llvm/Analysis/DominanceFrontier.h - Dominator Frontiers --*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines the DominanceFrontier class, which calculate and holds the
// dominance frontier for a function.
//
// CAUTION: For SSA-construction-like problems there are more efficient ways to
// do that, take a look at GenericIteratedDominanceFrontier.h/SSAUpdater.h. Also
// note that that this analysis computes dominance frontiers for *every* block
// which inherently increases complexity. Unless you do need *all* of them and
// *without* any modifications to the DomTree/CFG in between queries there
// should be better alternatives.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_DOMINANCEFRONTIER_H
#define LLVM_ANALYSIS_DOMINANCEFRONTIER_H

#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/IR/PassManager.h"
#include "llvm/Pass.h"
#include "llvm/Support/GenericDomTree.h"
#include <cassert>

namespace llvm {

class BasicBlock;
class Function;
class raw_ostream;

//===----------------------------------------------------------------------===//
/// DominanceFrontierBase - Common base class for computing forward and inverse
/// dominance frontiers for a function.
///
template <class BlockT, bool IsPostDom>
class DominanceFrontierBase {
public:
  // Dom set for a bb. Use SetVector to make iterating dom frontiers of a bb
  // deterministic.
  using DomSetType = SetVector<BlockT *>;
  using DomSetMapType = DenseMap<BlockT *, DomSetType>; // Dom set map
  using DomTreeT = DominatorTreeBase<BlockT, IsPostDom>;
  using DomTreeNodeT = DomTreeNodeBase<BlockT>;

protected:
  using GraphTy = std::conditional_t<IsPostDom, Inverse<BlockT *>, BlockT *>;
  using BlockTraits = GraphTraits<GraphTy>;

  DomSetMapType Frontiers;
  static constexpr bool IsPostDominators = IsPostDom;

public:
  DominanceFrontierBase() = default;

  /// isPostDominator - Returns true if analysis based of postdoms
  bool isPostDominator() const {
    return IsPostDominators;
  }

  void releaseMemory() {
    Frontiers.clear();
  }

  // Accessor interface:
  using iterator = typename DomSetMapType::iterator;
  using const_iterator = typename DomSetMapType::const_iterator;

  iterator begin() { return Frontiers.begin(); }
  const_iterator begin() const { return Frontiers.begin(); }
  iterator end() { return Frontiers.end(); }
  const_iterator end() const { return Frontiers.end(); }
  iterator find(BlockT *B) { return Frontiers.find(B); }
  const_iterator find(BlockT *B) const { return Frontiers.find(B); }

  /// print - Convert to human readable form
  ///
  void print(raw_ostream &OS) const;

  /// dump - Dump the dominance frontier to dbgs().
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  void dump() const;
#endif

  void analyze(const DomTreeT &DT);
};

class DominanceFrontier : public DominanceFrontierBase<BasicBlock, false> {
public:
  using DomTreeT = DomTreeBase<BasicBlock>;
  using DomTreeNodeT = DomTreeNodeBase<BasicBlock>;
  using DomSetType = DominanceFrontier::DomSetType;
  using iterator = DominanceFrontier::iterator;
  using const_iterator = DominanceFrontier::const_iterator;

  /// Handle invalidation explicitly.
  LLVM_ABI bool invalidate(Function &F, const PreservedAnalyses &PA,
                           FunctionAnalysisManager::Invalidator &);
};

class LLVM_ABI DominanceFrontierWrapperPass : public FunctionPass {
  DominanceFrontier DF;

public:
  static char ID; // Pass ID, replacement for typeid

  DominanceFrontierWrapperPass();

  DominanceFrontier &getDominanceFrontier() { return DF; }
  const DominanceFrontier &getDominanceFrontier() const { return DF;  }

  void releaseMemory() override;

  bool runOnFunction(Function &) override;

  void getAnalysisUsage(AnalysisUsage &AU) const override;

  void print(raw_ostream &OS, const Module * = nullptr) const override;

  void dump() const;
};

extern template class LLVM_TEMPLATE_ABI
    DominanceFrontierBase<BasicBlock, false>;
extern template class LLVM_TEMPLATE_ABI DominanceFrontierBase<BasicBlock, true>;

/// Analysis pass which computes a \c DominanceFrontier.
class DominanceFrontierAnalysis
    : public AnalysisInfoMixin<DominanceFrontierAnalysis> {
  friend AnalysisInfoMixin<DominanceFrontierAnalysis>;

  static AnalysisKey Key;

public:
  /// Provide the result type for this analysis pass.
  using Result = DominanceFrontier;

  /// Run the analysis pass over a function and produce a dominator tree.
  LLVM_ABI DominanceFrontier run(Function &F, FunctionAnalysisManager &AM);
};

/// Printer pass for the \c DominanceFrontier.
class DominanceFrontierPrinterPass
    : public RequiredPassInfoMixin<DominanceFrontierPrinterPass> {
  raw_ostream &OS;

public:
  LLVM_ABI explicit DominanceFrontierPrinterPass(raw_ostream &OS);

  LLVM_ABI PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
};

} // end namespace llvm

#endif // LLVM_ANALYSIS_DOMINANCEFRONTIER_H